1. Technical Field
The present invention relates to an organic EL (electroluminescence) element, a method for manufacturing an organic EL element, an organic EL device, and an electronic apparatus.
2. Related Art
An example of a method for manufacturing an organic EL element is disclosed, in which a functional layer including a light-emitting layer of an organic EL element is formed by a thin-film forming method of forming a thin-film layer by filling a region surrounded by a bank (partition wall) with a thin-film material solution (Japanese Unexamined Patent Application Publication. Nos. 11-271753 and 2008-135255).
Japanese Unexamined Patent Application Publication No. 11-271753 discloses an example in which a functional layer includes a hole transport layer and an organic semiconductor layer (light-emitting layer). The bank has a laminated structure including an affinity layer showing affinity for the thin-film material solution (containing a hole transport layer material or an organic semiconductor material) and a non-affinity layer showing non-affinity for the material. The laminated structure is formed by repeatedly laminating layers a number of times corresponding to the number of different material layers in the functional layer. The thickness of the lowermost affinity layer is substantially the same as the thickness of a thin film to be formed by drying the thin-film material solution. The total thickness of the lowermost affinity layer and the non-affinity layer laminated on the affinity layer is substantially the same as the thickness of a next thin film to be laminated.
Namely, a thin film formed by drying the thin-film material solution applied inside the bank is pinned by the side wall of the corresponding affinity layer, not by the non-affinity layer. Therefore, a thin film having a stable sectional shape and a laminated structure thereof can be realized.
Japanese Unexamined Patent Application Publication No. 2008-135255 discloses that an insulating individual partition wall which partitions pixel apertures of a plurality of organic EL elements disposed on a substrate, and a common partition wall formed around the individual partition wall with a space therebetween are provided. The common partition is made of a liquid-repellent material, and a liquid containing a light-emitting layer-forming material is applied to a region surrounded by the common partition and dried to dispose a light-emitting layer to cover the individual partition. As a result, the thicknesses of light-emitting layers in a plurality of organic EL elements are made more uniform. The individual partition may be formed by laminating a lyophilic layer and a liquid-repellent layer.
In the configuration of the bank of Japanese Unexamined Patent Application Publication No. 11-271753, when a next thin film is laminated on the lowermost thin film layer, the thin film is not securely pinned by the affinity layer on the non-affinity layer in a drying process unless the thin-film material solution is filled over the non-affinity layer in the height direction. That is, in fact, there is a problem that it is difficult to form each of the layers in the laminated structure-functional layer at a desired position in the height direction unless a region surrounded by the bank is uniformly filled with a predetermined amount of the thin-film material solution.
The configuration including the individual partition wall and the common partition wall described in Japanese Unexamined Patent Application Publication No. 2008-135255 is effective in forming a plurality of organic EL elements which produce a single luminescent color but is unsuitable for generating different luminescent colors between adjacent organic EL elements. This configuration also has the problem of being unsuitable for a display device and the like which are aimed at securing a predetermined numerical aperture because the size and arrangement of a light-emitting region defined by the individual partition wall are limited by an arrangement relation to the common partition wall.